Technical Field
The present invention relates to a focus depth extension imaging optical system, a focus depth extension element, and an imaging apparatus.
Description of Related Art
An imaging apparatus including an imagining element (hereinafter referred to as an image sensor) such as a CCD sensor and a CMOS sensor has been known as described in Patent Literature 1 (Japanese Laid-Open Patent Application No. 2011-227421). Patent Literature 1 describes a depth-of-field-extended optical system configured by adding a light modulation plate to an image forming optical system which images an image of a target. The depth-of-field-extended optical system is configured to restore an image having a deep depth of focus by executing a digital process on an image imaged by an image sensor.
In this specification, a depth of field is referred to as a depth of focus, an optical element that extends a depth of focus of an image forming optical system as the light modulation plate is referred to as a focus depth extension element, and an image forming optical system to which the focus depth extension element is added is referred to as a focus depth extension image forming optical system.
The light modulation plate of the depth-of-field-extended optical system described in Patent Literature 1 has a refracting power to match the peaks of the defocus MTF between the imaging only by the imaging optical system and the imaging by the depth-of-field extended optical system.